Characterization of indoor air quality and efficiency of air purifier in childcare centers, Korea

The house-dust mite (HDM), commonly found in human dwellings, is an important source of inhalant and contact allergens. In this report, the importance of HDM allergy in Korea and the characteristics of allergens from dust mite are reviewed with an emphasis on investigations performed in Korea. In Korea, Dermatophagoides farinae is the dominant species of HDM, followed by D. pteronyssinus. Tyrophagus putrescentiae is also found in Korea, but its role in respiratory allergic disease in Korea is controversial. The relatively low densities of mite populations and concentrations of mite major allergens in dust samples from Korean homes, compared to westernized countries, are thought to reflect not only different climatic conditions, but also cultural differences, such as the use of ‘ondol’ under-floor heating systems in Korean houses. HDM are found in more than 90% of Korean houses, and the level of exposure to HDM is clinically significant. About 40%-60% of Korean patients suffering from respiratory allergies, and more than 40% of patients suffering from atopic dermatitis, are sensitized to HDM. Mite allergens can be summarized according to their inherent auto-adjuvant activities and/or their binding affinities to the adjuvant-like substances: proteolytic enzymes, lipid binding proteins, chitin binding proteins, and allergens not associated with adjuvant-like activity. In general, allergens with a strong adjuvant-like activity or adjuvant-binding activity elicit potent IgE reactivity. In Korea, Der f 2 is the most potent allergen, followed by Der f 1. Immune responses are modulated by the properties of the allergen itself and by the adjuvant-like substances that are concomitantly administered with the antigens. Characterization of allergenic molecules and elucidation of mechanisms by which adjuvant-like molecules modulate allergic reactions, not only in Korea but also worldwide, will provide valuable information on allergic diseases, and are necessary for the development of diagnostic tools and therapeutic strategies.

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House Dust Mite Allergy in Korea: The Most Important Inhalant Allergen in Current and Future

Seasonal variation of air quality in hospitals with indoor–outdoor correlations

Efficiency of portable HEPA air purifiers against traffic related combustion particles

Positive and negative streamer discharges in atmospheric pressure air were generated in a shielded sliding discharge reactor at operating voltages as low as 5 kV for a gap length of 1.6 cm. In this reactor, electrodes are placed on top of a dielectric layer and one of the electrodes, generally the one on ground potential, is connected to a conductive layer on the opposite side of the dielectric. The energy per pulse, at the same applied voltage, was more than a factor of seven higher than that of pulsed corona discharges, and more than a factor of two higher than that of sliding discharges without a shield. It is explained on the basis of enhanced electric fields, particularly at the plasma emitting electrode. Specific input energy required for 50 % removal from ~1,000 ppm initial NO could be reduced to ~18 eV/molecule when ozone in the exhaust of negative streamers was utilized. For sliding discharges and pulsed corona discharges this value was ~25 eV/molecule and it was 35 eV/molecule for positive shielded sliding discharges. Also, the ozone energy yield from dry air was up to ~130 g/kW h and highest for negative streamer discharges in shielded sliding discharge reactors. The high energy density in negative streamer discharges in the shielded discharge reactor at the relatively low applied voltages might not only allow expansion of basic studies on negative streamers, but also open the path to industrial applications, which have so far been focused on positive streamer discharges.

Nitric Oxide Conversion and Ozone Synthesis in a Shielded Sliding Discharge Reactor with Positive and Negative Streamers

PURPOSE The effects of air cleaners on the removal of airborne indoor allergens, especially house dust mites (HDM), are still controversial. The objective of this study is to evaluate the effect of an air cleaner with an electrostatic filter on the removal of airborne mite allergens. MATERIALS AND METHODS A dried HDM culture medium that contained mite body particles and excretions was dispersed in a chamber equipped with an electrostatic air cleaner. The number of airborne particles was recorded continuously by a dust spectrometer for 60 minutes. Airborne particles in the chamber were collected on a sampling filter at a flow rate of 10 L/min and the Der f 1 concentration in the filter extracts was measured by two-site ELISA. RESULTS The air cleaner efficiently removed airborne HDM particles. The air cleaner removed airborne HDM particles (size 2-12.5 µm) 11.4 ± 2.9 fold (cleaner operating for 15 minutes), 5.4 ± 0.7 fold (cleaner operating for 30 minutes), and 2.4 ± 0.2 fold (cleaner operating for 60 minutes) more than the removal of HDM particles by natural settle down. Removal kinetics differed according to the particle size of the airborne particles. The air cleaner decreased the concentration of Der f 1 in the extraction of airborne particles collected on the air sampling filter by 60.3%. CONCLUSION The electrostatic air cleaner can remove airborne HDM allergens and may be useful as a supplementary environmental control tool for HDM sensitized respiratory allergic patients.

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Santosh Rani Agrawal

Papers

Effect of an Air Cleaner with Electrostatic Filter on the Removal of Airborne House Dust Mite Allergens